Table 2.

Chemical, pharmacologic, and microbiologic characteristics of selected parenteral cephalosporins used to treat infections caused by Neisseria gonorrhoeae.

Cephalosporin Usual Dose (Alternate Dose)	Chemical Structure*	Peak Serum Level** (mg/L)	Half Life** (hrs)	Serum Level 10 hours after peak (mg/L)*****	Hypothetical MIC90 limit*** (10hr conc/4) (mg/L)	Breakpoints (CLSI unless indicated otherwise)
Ceftriaxone 125mg or 250mg (pk data for 125mg)		13.5	5.8–8.7	4.086–6.086	1.022–1.521	S: ≤0.25**** I: ND R: ND
Cefuroxime 1500mg		13.6	1.3	0.066	0.016	(IV formulation) S: ≤1 I: 2 R: ≥4
Ceftizoxime 500mg		13	1.1–2.3	0.024–0.638	0.006–0.160	S: ≤0.5 1:ND R:ND
Cefodizime 1000mg		75	2.5–4	0.141–0.446	0.035–0.112
Cefotaxime 1000mg		20.5	0.8	0.001–0.054	0–0.013

S= sensitive; I=Intermediate; R=resistant; ND=Not determined

^*Source of chemical structures is the Kyoto Encyclopedia of Genes and Genomes Drug database available at: http://www.genome.jp/kegg/drug/ (Accessed August 23, 2008)

^**Source of elimination half life and peak concentration is Micromedex DRUGDEX® Evaluations, Thomson Healthcare. http://www.micromedex.com (Accessed September 30, 2008)

^***Moran JS, Levine WC. Drugs of choice for the treatment of uncomplicated gonococcal infections. Clin Infect Dis 1995 Apr;20 Suppl 1:S47-65.³²

^****Other authors and organizations have picked lower cutpoints to define isolates that are “less susceptible.” For example, the European Surveillance of Sexually Transmitted Infections (ESSTI) network uses 0.125 as the upper limit of sensitivity.⁵¹

^*****serum concentration at time $t=\frac{C_{\max }}{e^{\frac{t(0.693)}{t_{1/2}}}}$